The proposed shared instrumentation grant is requesting funds to purchase a flow cytometer which would provide the basis for establishing a flow cytometry center at the University of Missouri-Columbia campus. This instrument would be utilized by the major users and the secondary group of users to analyze and/or sort various populations of primary or cultured cells. Research projects which will rely heavily on the flow cytometer include the study of the mechanisms by which Pseudomonas exotoxin A activates T lymphocytes, the study of T lymphocyte differentiation, the role of lymphoid cells in the induction of autoimmune thyroiditis, the contraceptive steroid effects in autoimmune mice and the analysis of the role of lymphocytes in uveal tract melanocyte destruction in melanoma bearing swine. Other research projects include the studies of retinal pigment epithelial cells, Bordetella cell surface antigen expression in recombinant vaccinia virus, analysis of antigen expression in transgenic mice and pigs, etc. The funds are being requested for the following reasons: The University of Missouri-Columbia, which includes the School of Medicine, does not have a flow cytometer. At the present time, the only available flow cytometer is leased by the University Hospitals and Clinics, Department of Pathology, and has preferential usage for clinical specimens. As this instrument is also being utilized to analyze referred clinical samples from nearby communities, the available usage time is limited. All of the proposed major users have previously purchased time from the University Hospitals. However, with the increased demand for analysis of clinical samples, access has become impossible to schedule. Dr. Misfeldt will be responsible for the flow cytometer. He will also be trained in the operation of the instrument and this training will be provided by the company supplying the instrument. A committee composed of three of the major users, plus Dr. Kim Wise, will meet regularly to decide on priorities for utilization of flow cytometry time. In addition, the School of Medicine has committed internal funds for at least one year to support a scientist who will be directly responsible for the everyday operation and maintenance of the instrument.